Retinitis pigmentosa is an eye disorder and is the name given to a group of hereditary diseases of the retina - the light sensitive tissue in the back of the eye. The retina slowly degenerates and gradually loses its ability to transmit images to the brain, resulting in a progressive loss in vision. Cells from the pigmented layer of the retina migrate into the nerve cell containing layer, causing a typical pattern of black or brown star shapes in the retina that give the diseases their name.

Age of onset and worsening
Symptoms of retinitis pigmentosa usually become apparent between the ages of ten and 30. Patients typically lose night vision in adolescence, side vision in young adulthood, and central vision in later life because of progressive loss of rod and cone photoreceptor cells. Yearly evaluation of the progression of the disease is recommended.

Retinitis Pigmentosa treatment with supplements
Fish oils supplements or DHA could be useful, along with lutein carotenoid.

Invest Ophthalmol Vis Sci. 2015. Docosahexaenoic Acid Slows Visual Field Progression in X-Linked Retinitis Pigmentosa: Ancillary Outcomes of the DHAX Trial. Docosahexaenoic acid (DHA) was supplemented in a single-site, placebo-controlled, randomized clinical trial designed to slow vision loss associated with X-linked retinitis pigmentosa (XLRP); the DHAX Trial. Male participants with XLRP (range, 7-31 years) received 30 mg DHA/kg/d (n = 29) or placebo (n = 22) for 4 years. Visual outcomes were measured annually and red blood cell (RBC) DHA determined every 6 months. Oral DHA supplementation increased mean RBC-DHA levels by 4-fold over placebo. No group differences in progression were found for visual acuity, shape discrimination, or fundus appearance. Yearly rates of progression were reduced for dark-adapted thresholds and visual field sensitivity for foveal, macular, peripheral, total, and ellipsoid zone regions by DHA supplementation. Supplementation of DHA significantly elevated blood DHA levels and reduced the rate of progression in final dark-adapted thresholds and visual field sensitivity. From the relationship between RBC-DHA and the rate of field sensitivity loss, we can extrapolate that an RBC-DHA level of 17% could minimize the decline in field sensitivity.

Chlorogenic acid
J Korean Med Sci. January 2014. Chlorogenic Acid supplementation improves multifocal electroretinography in patients with retinitis pigmentosa. To evaluate the effect of chlorogenic acid supplementation in patients with retinitis pigmentosa, we evaluated objective change in visual function with multifocal electroretinography, along with visual acuity, visual field, standard electroretinography, and contrast sensitivity. Eighteen patients diagnosed with retinitis pigmentosa were enrolled in this prospective, non-comparative, single-arm study. Multifocal electroretinography, best-corrected visual acuity in Early Treatment Diabetic Retinopathy Study letters, total point score on visual field examination with Humphrey Field Analyzer II, electroretinography, and contrast sensitivity were measured and repeated after 3 months supplementation with chlorogenic acid. The amplitude of ring 5 was significantly higher on multifocal electroretinography after 3 months of chlorogenic acid supplementation. There were no significant changes in the best-corrected visual acuity, total point score on Humphrey Field Analyzer, 30 Hz flicker amplitude on standard electroretinography, or contrast sensitivity. Chlorogenic acid may have a beneficial effect on the peripheral area at the margins of retinal degeneration, and should be considered as an anti-oxidant for the management of retinitis pigmentosa.

Lutein
Clinical trial of lutein in patients with retinitis pigmentosa receiving vitamin A.
Arch Ophthalmol. 2010. Berman-Gund Laboratory for Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA.
Randomized, controlled, double-masked trial of 225 nonsmoking patients, aged 18 to 60 years, evaluated over a 4-year interval. Patients received 12 mg of lutein or a control tablet daily. All were given 15,000 IU/d of vitamin A palmitate. Randomization took into account genetic type and baseline serum lutein level. The primary outcome was the total point score for the Humphrey Field Analyzer (HFA) 30-2 program; prespecified secondary outcomes were the total point scores for the 60-4 program and for the 30-2 and 60-4 programs combined, 30-Hz electroretinogram amplitude, and Early Treatment Diabetic Retinopathy Study acuity. No significant difference in rate of decline was found between the lutein plus vitamin A and control plus vitamin A groups over a 4-year interval for the HFA 30-2 program. For the HFA 60-4 program, a decrease in mean rate of sensitivity loss was observed in the lutein plus vitamin A group. Mean decline with the 60-4 program was slower among those with the highest serum lutein level or with the highest increase in macular pigment optical density at follow-up. Those with the highest increase in macular pigment optical density also had the slowest decline in HFA 30-2 and 60-4 combined field sensitivity. No significant toxic effects of lutein supplementation were observed.  Lutein supplementation of 12 mg/d slowed loss of midperipheral visual field on average among nonsmoking adults with retinitis pigmentosa taking vitamin A. Application to Clinical Practice Data are presented that support use of 12 mg/d of lutein to slow visual field loss among nonsmoking adults with retinitis pigmentosa taking vitamin A.

Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial.
BMC Ophthalmol. 2006. Bahrami H, Melia M, Dagnelie G. The Wilmer Eye Institute, Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
There is no generally accepted medical or surgical treatment to stop the progressive course of retinitis pigmentosa. Previous studies have suggested lutein as a potential treatment with positive effects on macular pigment density. The objective of this study was to examine the effect of lutein supplementation on preservation of visual function in patients with retinitis pigmentosa. In a double-masked randomized placebo-controlled phase I/II clinical trial with a cross-over design, 34 adult patients with retinitis pigmentosa were randomized to two groups. One group, consisted of 16 participants, received lutein supplementation (10 mg/d for 12 wks followed by 30 mg/d) for the first 24 weeks and then placebo for the following 24 weeks, while the other group included 18 participants for whom placebo (24 weeks) was administered prior to lutein. For visual acuity (VA) at normal illumination level, treatment with lutein reduced logMAR, i.e. improved VA, but this effect was not statistically significant. Lutein had a statistically significant effect on visual field and this effect increased in the model assuming a 6-week delay in effect of lutein. These results suggest that lutein supplementation improves visual field and also might improve visual acuity slightly, although these results should be interpreted cautiously. As a combined phase I and II clinical trial, this study demonstrated the efficacy and safety of lutein supplementation.

DHA and fish oils
Invest Ophthalmol Vis Sci. 2015. Docosahexaenoic Acid Slows Visual Field Progression in X-Linked Retinitis Pigmentosa: Ancillary Outcomes of the DHAX Trial. Supplementation of DHA significantly elevated blood DHA levels and reduced the rate of progression in final dark-adapted thresholds and visual field sensitivity.

Further evaluation of docosahexaenoic acid in patients with retinitis pigmentosa receiving vitamin A treatment: subgroup analyses.
Arch Ophthalmol. 2004. Berson EL, Rosner B, Sandberg MA, Weigel-DiFranco C, Moser A, Brockhurst RJ, Hayes KC, Johnson CA, Anderson EJ, Gaudio AR, Willett WC, Schaefer EJ. Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, 243 Charles Street, Boston, MA
To determine whether docosahexaenoic acid will slow the course of retinal degeneration in subgroups of patients with retinitis pigmentosa who are receiving vitamin A. A cohort of 208 patients with retinitis pigmentosa, aged 18 to 55 years, were randomly assigned to 1200 mg of docosahexaenoic acid plus 15 000 IU/d of vitamin A given as retinyl palmitate (DHA + A group) or control fatty acid plus 15 000 IU/d of vitamin A (control + A group) and followed up over 4 years. Seventy percent of the patients in each group were taking vitamin A, 15 000 IU/d, prior to entry. We compared rates of decline in ocular function in the DHA + A vs control + A groups among the subgroups defined by use or nonuse of vitamin A prior to entry. We also determined whether decline in ocular function was related to red blood cell phosphatidylethanolamine docosahexaenoic acid level, dietary omega-3 fatty acid intake, or duration of vitamin A use. Main outcome measures were Humphrey Field Analyzer visual field sensitivity, 30-Hz electroretinogram amplitude, and visual acuity. Among patients not taking vitamin A prior to entry, those in the DHA + A group had a slower decline in field sensitivity and electroretinogram amplitude than those in the control + A group over the first 2 years; these differences were not observed in years 3 and 4 of follow-up or among patients taking vitamin A prior to entry. In the entire cohort, red blood cell phosphatidylethanolamine docosahexaenoic acid level was inversely related to rate of decline in total field sensitivity over 4 years. This was particularly evident over the first 2 years among those not on vitamin A prior to entry. In the entire control + A group, dietary omega-3 fatty acid intake was inversely related to loss of total field sensitivity over 4 years. The duration of vitamin A supplementation prior to entry was inversely related to rate of decline in electroretinogram amplitude. For patients with retinitis pigmentosa beginning vitamin A therapy, addition of docosahexaenoic acid, 1200 mg/d, slowed the course of disease for 2 years. Among patients on vitamin A for at least 2 years, a diet rich in omega-3 fatty acids slowed the decline in visual field sensitivity.

Vitamin A and beta carotene
JAMA Ophthalmol. 2013. Treatment with 9-cis β-carotene-rich powder in patients with retinitis pigmentosa: a randomized crossover trial. Treatment with 9-cis β-carotene significantly increased retinal function in patients with RP under the tested conditions.

Cochrane Database Syst Rev. Dec 19 2013. Vitamin A and fish oils for retinitis pigmentosa. Based on the results of three RCTs, there is no clear evidence for benefit of treatment with vitamin A and/or DHA for people with RP, in terms of the mean change in visual field and ERG amplitudes at one year and the mean change in visual acuity at five years follow-up.

Studies in preterm and term human infants have suggested that a dietary supply of omega-3 fatty acids is essential for optimal visual development. Several basic science studies support the hypothesis that omega-3 fatty acids may be useful therapeutic agents for pathologies of the retina and lens. As part of a systematic review of the effect of omega-3 fatty acids on eye health, the purpose of this study was to conduct a systematic review of the scientific-medical literature to appraise and synthesize the evidence for the effects of omega-3 fatty acids in preventing the development or progression of retinitis pigmentosa. There are trends in improvement of some retinitis pigmentosa outcomes with omega-3 fatty acids in the higher quality studies. Clinical research is preliminary in this field, however. Accordingly, definitive answers will require significantly more observational and interventional clinical research. Can J Ophthalmol. 2006 Aug. The evidence for efficacy of omega-3 fatty acids in preventing or slowing the progression of retinitis pigmentosa: a systematic review. Department of Opthalmology, Ottawa Hospital Eye Institute, University of Ottawa, Ont., Canada.

Medical treatment
Curr Stem Cell Res Ther. 2015. Recent advances in treatment of retinitis pigmentosa. Retinitis pigmentosa (RP) is a group of inherited retinal disorders characterized by the progressive photoreceptors and pigment epithelial cells dysfunction. It is the most common retinal degeneration, responsible for loss of vision of most people worldwide. Until now its exact pathogenesis and etiology are not clear. So far there is no approved therapy. New approaches for RP therapy include cell transplantation, gene therapy, cytokine therapy, nutrition therapy, and hyperbaric oxygen therapy. Such therapies for retinal degenerative diseases are limited in their efficacy.